Railway signaling system



J. c. HOFFMAN 1,874,291

RAILWAY SIGNALING SYSTEM Filed Nov. 16, 1931 4 Sheets-Sheet l Aug. 30, 1932.

Y a m 2 INVENTOR JHY C 0F'PNN- WNW ATTORNEY Aug. 30, 1932. HOFFMAN 1,874,291

RAILWAY SIGNALING SYSTEM Filed Nov. 16. 1931 4 sheets-sneak 2 INVENTOR ATTORNEY -A ug. 30, 1932.

J. CL HOFFMAN RAILWAY SIGNALING SYSTEM Filed Nov. 16. 1931 4 Sheets-Sheet 5 INVENTOR E L W Aug. 30, 1932. g, HOFFMAN 1,874,291

RAILWAY SIGNALING SYSTEM Filed Nov. 16. 1931 4 Sheets-Sheet 4 rks- 5 INVENTOR ATTO RNEY Patented Aug. 30, 1932 UNITED. TAT S JAY c. norrnlumor Anon, onro RAILWAY sIeNAtme SYSTEM Application filed November 16, 1981. Serial No. 575,390.

My invention relat'esto railway signaling systems, such as automatic electric blocksignal systems, using direct current and a normally closed track circuit. In such systems the automatic operation of the track circuit between successive automatic block signals is greatly afiec'ted by changes in weather conditions or the seasons." Thus, during wetweather periods a considerable amount of electric current leaks from rail to rail through the wet ballast and cross ties, and a'greater amount of energy or current is required at thistimeto operate the track circuit than in dry weather. Accordingly, the current flow in the track circuitmust be regulated, otherwiseunder one condition the track relays, controlling the circuits for the block signals, become less sensitive in response to a train shunt, and under another condition there'is danger of the relays remaining energized and producing a false signal indication. At present such conditions in'a track circuit are partly controlledby an adjustable resistance unit connected in series with the battery of the circuit and so adjusted that the current flowing in said circuit is sufficient to actuate the track relay when maximum current losses are experienced, To reduce the losses itis also customary to subdivide the track circuit between two block signals in two circuit sections and tohave inspectors and repairmen adjust the adjustable resistances prior to wet and dryweat'her seasons, so that the system may function effectively during such seasons. i y t It has also been proposed toprovide automatic means for regulating the current flow in the track circuit which will automatically cut in a resistance in serieswith a normally closed track circuit when the current flow therein reaches a predetermined energy, thereby maintaining or increasing the sensitiveness of the circuit to a train or car shunt. The meansu'sed in such automatically regulated track circuit is an ordinary tractive armature direct current relay; The operating characteristics of such relay are such Still better holding the same in attracted position. Thus, these energies difi'er up to sixty percent and therefore cause ineffectiveness in the automatic adjusting means over a substantial area of resistance changes in the resistance ofthe track circuit. The generalobject of my present invention is to regulate the current flowing in a track circuit more readily and accurately by providing more sensitive automatic regulating means. F or such pur- .pose' I use a special tractive armature direct current relayembodying a common electromagnet with two coils and a resistance element adapted to be interposed between the coils of said electro-magnet, when the armature is attracted.v This resistance reduces the .force of the magnetto such a degreethat a slight decrease of the current flowing through the magnet will cause release of the armature, and consequently the armature in this relay is picked up orreleased within close energy ranges.

results according to my invention will beaccomplished by. the use of special tractive armaturedirect current relays 7 provided with a series of armatures, preferably two, supported opposite each other and adapted .to be successively'picked up within leased within-narrow ranges of the current flowingthrough the coils of the relay.

Two of these self-regulatingrelays are used to control the track circuit and are so coupled with each other and the circuit that one relay regulates the current flow in the track circuit when its track isunoccupied, and the second relay gets in action when such track is bridged by a train or can. y

In the accompanying drawings, Figs. 1 and 2 are side and front elevations, respectively, partly in section, of a relay constructed to carry out my conception and invention. Figs.

3, 4, and 5, are diagrams of a section or block of a railway signaling system having such a relay in circuit therewith, and showing the operation thereof under diiierent conditions.

The relay A shown in Figs. 1 and 2 is in some respects similar to the direct current tractive armature relays ordinarily used for the same purpose, in that it embodies a pair of magnet windings or coils 2 and 3, and a pair of pole pieces 4 and 5, respectively, mounted on a suitable base 6 carrying any desired or required number of binding posts7 to 10, to permit the device to be connected electrically to a railway signalin'g'syste'm. The relay also includes two armatures B and C,

t I arranged symmetrically with respect to each other and hinged oppositethe ends ofthe .pole pieces 4- and '5 to a bracket member 11.

Armatures, B and C carry circuit make and break devices D and E respectively to make and break connection between posts 7 and 8 and posts 9 and 10. Thus, device D on armature B is electrically connected by wire 12 and strip 1 1 with post 8 and cooperates with a contact member 15 on post 9.

The features which distinguish relay A from others known to me reside mainly in the use of the two armatures B and C, the coupling of a resistance element or coil in series with the magnet coils 2, and 3, and the use of co-operating finger portions or extensions 16, 17, and armatures Band C respectively to insure simultaneous release of said armatures.

The relay is so adjusted that'armature B is picked up, when a predetermined current flows through the magnet coils 2and 3,- and armature C willbeattracted,'when the current flowing through coils 2 and 3 slightly "increases. Such adjustment is made by changing the air-gap distance between the magnet yoke and pole pieces and is commonly used for securing different operating values of tractive armature relays.

The action of the relay is as follows: A predetermined flow of currentthrough the magnet coils 2 and 3-will create a magnetic force sufiicient to attract armature B, and a slight increase of such -magnetic'force effected by increase of current flow in coils 2 and 3, will pick up armature C. Attraction of armature C causes its circuit make and break device E to engage with spring contact member F and break the contact of F with member 15 0f the shunt line for resistance element W, interposed in the circuit between magnet coils 2 and 3. The predetermined resistance of element W reduces the current flow in coils 2 and 3 and the magnetic force of the relay to such'a degree that'sli'ght decrease of the currentfiow will effect release "of armatures B and'C, from pole pieces 4:

current i-n-thetrack circuit, fed by battery M. Relays A and A are similar in construction with the'exception that relay A embodies coils-with difierential windings, viz., low resistance windings O, and high resistance windings Qan'd 8. The magnet coils 2 and 3 of relay A are of the single winding type.

'In the closed= track circuit relays A, A, adj ustable resistance elements, local connecting circuitsandbattery M, are arranged at one end, 'adjacent' signats, whereas a track relay T of ordinary type-is arranged at the opposite end of said'track circuit adjacent to signal S.

The resistance'L is-soadjusted that the magnetic field of low resistingwinding O is insufiicient toipick up armatures B or C of relay A and that whensgreatest losses through cross ties and ballast occur the current flowing through the track circuit and the auxiliaryenerg-izing circuits is insufficient to cause picking up of armatures B,C and B, C

respectively sot-hat these armatures stay dropped, but such current must be suilicient to actuate track relay'T. Under these conditions the current flows from battery M through adjustable resistance L-to contact '13, makerand break deviceDofarmature B and-low resistance-windings O of relay A,

thence contact 13 'and make'and break deviceD of armatureB of relay A to rail 16, coils of relay T, returning over rail 16 to battery M. A negligible amount of current is shunted through an auxiliary energizing circuit of relay-A, beginning at contact '18 and leading through resistanceK, its terminal R windings Q, contact 15 and windin gs 3 to battery M.

A decrease of the current-losses through cross ties and ballast increases the flow of energizing circuit of relay A described above. When such losses have been substan- I tially reduced,-as in-=a dry'weather period,

the current --in the closed track circuit will resemble the'diagram represented in Figure 4, which diagram shows that the current energy in the track circuit and auxiliary" energizing circuit has'been automaticzvlly regulated by change of the. path of the current inthe closed track circuit. Thus the current in the track circuit flows from battery 'M through resistance L to contact 13', make and break de vice -of armature B, and low resistance windings O, of relay A, thence to contact 13',

I the auxiliary energizing circuit beginning at contact 13 flows through resistance K, its terminal K windings 2' resistance W and windings 3 to battery M. This change of the path of the current of the track circuit 1 and the auxiliary energizing circuits has been caused by the increase of the current flowing through the circuits delineated in the diagram of Figure 3. Thus the increase of current in the auxiliary energizing circuit has caused picking up of armature B and therewith insertion of resistance K into the track circuit, which resistance previously was shunted out by make and break device D. The increase oi resistance in the track circuit in turn increased the flow of current through the auxiliary energizing circuit with coils 2 and 3 and caused picking up of armature C of relay A, which in turn caused breaking ofcontact 15 and interposing of resistance WV between coils 2 and 3, which resistance, in

dropped position of armature C, bridges the auxiliary energizing circuit at contact 15'.

Short circuiting of the track circuit by a wheeled truck or car causes the current flow in the track circuit to follow the diagram shown in Figure 5 which shows that the wheels and axles of the truck short circuit that part of the track circuit which includes relay T, so that said relay releases its armature U, in turn actuating a signaling circuit P for signal S. The current in the shunted track circuit flows from battery M through resistance L to and through resistance H, its terminal H low resistance windings O of relay A, thence to contact 13, break and make device D of armature B of relay A and to rail 16, returning through the axles of the truck over rail 16 to battery M. The current in the auxiliary energizing circuit flows from resistance H over its terminal H to windings 3 resistance W and winding 2 to the low resistance winding 0.

The described paths of current in the track circuit and the auxiliary energizing circuits are brought about by the short increases of the flow of current in the track circuit and the auxiliary energizing circuits for relay A and A, considerably in excess of the amount flowing in said circuit during wet weather periods. Consequentl the potential between the K terminal 0 resistance K and the battery is so materially decreased, that only a negligible amount of current will flow through coils 2 and 3, and armatures B and C of relay A are released. Release of said armatures of course-shunts resistance K out of the circuit and thereby increases the current flow through resistance L contact 13, member D and low resistance coil the magnet coil windings 2 and 3.

member D -of relay A and through the track.

rails. This increased current flow'is sufiicient to causearmature B of relay A to be icked up, thus causing contact 13 and memerD to become disconnected and to switch ranged in the auxiliary energizing circuit for relay A so that armatures B and O are practically simultaneously picked up, thus cutting additional resistance H into the track circuit. At the same time as member E causes a break in contact between spring member F and contact 15, resistance W bridging-said contact is interposed between This resistance causes a reduction of current flow in the high resistance windings 2 and 3 which together with the reduced fiow of current in the low resistance windings 0 will readily permit release of armature B and U when the short circuit of the track is broken by moving the wheeled car or truck out of the track circuit. a

What I claim,is:

1. Ina railwa signaling system, a normally-closed track circuit, a source of electric current for said circuit, means .for manually'regulating the amount of current appliedto said circuit, a signaling circuit, a relay in said track circuit for controlling said signaling circuit, resistance means within said track circuit, tractive armature relay means for short-circuiting said resistance means under predetermined settings of said current regulating means, said relay means including a resistance and switching elements for shunting the resistance ofsaid relay means when the armature of said relay 'meansis in oif position.

2. In a railway signaling system a signaling circuit, a track circuit, a relay in said track circuit for actuating said signaling circuit, a tractive armature relay and a resistance for automatically controlling the flow of current insaid track circuit and an adjustable resistance in series with the coils of said tractive armature relay, the armature of said tractive armature relay including switching means to shunt said resistance and said adjustable resistance for automatic control of the current flow in. said track circuit and for pick up and release of said armature within narrow ranges of current values flowing through said relay.

3. In a railway signaling system, a signaling circuit, a normally closed track circuit, a relay in said track circuit controlling said signaling circuit, means for regulating the amount of electric current for said track circuit, a tractive armature relay for automatically controlling the flow of current within said track circuit, resistance means '70 an additional resistance H into the track circult, which causes increase of current flowing through high resistance co1ls 2 and 3 arfor said track circuit and a resistance for said tractivearmature relay, said tractive armature relay including two symmetrically arranged armatures andswitching means so actuated by said armatures that one armature shunts the resistance for said track circuit and the. other the resistance for the. trac- -tive armature relay for automatic control of the current flow in said track circuit and .for pick up and release of said armatures within narrow, ranges of current values flowing through said relay.

4;. In a railway signaling system, comprising a signaling circuit, and a normally closed track circuit with a relay for operating said signaling circuit and shuntable resistance means for controlling the flow of current within said track circuit, a tractive armature relay connected to the track circuit and having an adjustable resistance, two symmetrically arranged armatures and switching means for each of said armatures for individual control of said resistance means and said adjustable resistance respectively.

5. In a railway signaling device, a track circuit, two tractive armature relays and resistances for automatically controlling the flowof current through said circuit, each of said relays including symmetrically arranged armatures, two magnet coils, and adjustable resistance element adapted to be connected in series therewith, and make and break devices operatively controlled by said armatures, one ofthe armatures of each of said relays and its make and break device being adapted to place the coils and the adjustable resistance of its relay in series when the elec- .triccurrentflowingthroughsaid coils reaches a predetermined strength and one of said relays including a low resistance coil and being so coupled with the other of said relays and said track circuit that the latter relay controls the current flow while saidtrack is unoccupied and said other relay controls such flow when said track is occupied.

In testimony whereof I affix my signature.

' JAY C. HOFFMAN. 

